Charge order textures induced by non-linear lattice coupling in a half-doped manganite

TL;DR

This study uses cryogenic electron microscopy to directly visualize local charge order and lattice interactions in a manganite, revealing how nonlinear lattice coupling influences electronic self-organization and ground state selection.

Contribution

It introduces a novel microscopy approach to map intra-unit-cell order and uncovers the role of nonlinear lattice coupling in charge order textures in manganites.

Findings

Direct imaging of charge order and coexistence of intermediate states

Identification of lattice mode coupling controlling ground states

Demonstration of local symmetry breaking at the nanoscale

Abstract

The self-organization of strongly interacting electrons into superlattice structures underlies the properties of many quantum materials. How these electrons arrange within the superlattice dictates what symmetries are broken and what ground states are stabilized. Here we show that cryogenic scanning transmission electron microscopy enables direct mapping of local symmetries and order at the intra-unit-cell level in the model charge-ordered system Nd$_{1/2}$Sr$_{1/2}$MnO$_{3}$. In addition to imaging the prototypical site-centered charge order, we discover the nanoscale coexistence of an exotic intermediate state which mixes site and bond order and breaks inversion symmetry. We further show that nonlinear coupling of distinct lattice modes controls the selection between competing ground states. The results demonstrate the importance of lattice coupling for understanding and manipulating the character of electronic self-organization and highlight a novel method for probing local order in a broad range of strongly correlated systems.